Measuring Earth’s Biomass

The Earth’s biomass is the mass of all living organisms, both animal, plant and bacterial. The biomass is spread throughout the oceans, land and to a much lesser extent in the atmosphere.

NASA (National Aeronautics and Space Administration) has been able to monitor the effects humans are having on the planet eco-sphere and the plant biomass because of years of data collected from their observation satellites, some of which have given over ten years of consistent data. One such satellite is SeaStar which has used its SeaWiFS(Sea-viewing Wide Field-of-view Sensor) instrument to monitor the oceans since 1997. The ocean is a larger bio-mass than the land and its state of health is fundamental to the health of the entire planet.

Another NASA satellite called Terra has been orbiting since 1999 and monitoring the planet with its MODIS (Moderate-resolution Imaging Spectroradiometer) instrument. The biomass information it provides allows scientists to provide Enhanced Vegetation Index (EVI) values that are based on the quantity of absorbed and reflected near infra-red from plants. Using a tree as an example, the more ‘green’ foliage the plant has, or the larger it is, the bigger is the EVI as the plant reflects less visible light and reflects more near infra-red (the same wavelength of the electromagnetic spectrum that are used by night-vision goggles).

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The image shows a collage of the entire planet and the land surface biomass measured by the MODIS instrument on TERRA. The video shows the ocean plankton blooms measured by the SeaWiFS instrument. The phytoplankton in the world oceans, such as those shown in these blooms, are responsible for over half the world’s oxygen supply.

It is essential to measure the earth’s biomass and understand changes that could be happening due to climate change so there are more earth observation satellites planned. One future ESA (European Space Agency) satellite is called BIOMASS and the satellite mission is designed to greatly improve estimates of land carbon storage and changes by monitoring global measurements of forest biomass over time. The information will give an in-depth view of the health of the world’s forests and their carbon cycle. It will use a 435MHz P-band synthetic aperture polarimetric radar. It is hoped to provide detailed measurements of polar ice sheets, subsurface geology and forest biomass. ESA is going to decide whether or not to fund the BIOMASS satellite in early January 2009.

Even though the spacecraft design, construction and launch will not be carbon neutral, unless ESA and NASA choose to buy offsets, the information they provide is essential for scientists to have the data required to convince the politicians, and any remaining sceptics, of the challenges faced by the world in tackling the climate crisis and its effects.